Mage Slayer

Wether it be from hatred for magic, jealousy of those talented in it , or any other reasons, you have trained specifically to combat those proficient in the arcane arts.

Arcane proficiency

Due to your research into countering magic you have great knowledge of spells and what they look like as they are being casted.

You gain proficiency or expertise if you already have proficiency in arcana

Knowledge of the Mage Slayers

Whilst researching counters to the arcane you came across a group of others like you. They left some of their knowledge for you to use.

Whenever a creature within 10 feet of you casts a spell you can use a reaction to make an opportunity attack

Magic Absorption

During your years fighting you have learned how to better endure and dodge spells.

As a reaction you can cast absorb elements a number of times equal to your proficiency bonus per short rest

Third Wind

You have grown relentless towards magic users allowing you to fight on even if you are exhausted.

When you enter combat and have no second wind uses you can roll a d6, if you roll above a 3 you regain a use of second wind

Ancient arcane wisdom

During your travels you have learned even more about magic.

you gain advantage when rolling arcana and advantage on all saving throws made against spells

you may also cast detect magic once per short rest

Arcane Flaw

You have learned how to exploit the flaws in a mages spells allowing you to counter swiftly.

Whenever a creature within 30 feet casts a spell you can use a reaction to teleport to said mage and make an opportunity attack. You could also expend a second wind charge to increase the range to 60 Feet

you may do this once per encounter 

you may also cast counter spell at level 4 expending a second wind charge 

Flow

As a bonus action you enter a state of intense focus that allows you to even see the flow of magic for 2 minutes( 20 rounds) allowing you to cast counter spell at no cost an unlimited number as long as you maintain concentration 

 you may do this once per long rest

Magic Vanquisher

You understanding of magic has reached such a level you can even prevent the use of it

you can cast counterspell 

you may only do this an amount of times equal to your proficiency bonus per long rest, if you run out of uses you may expend a second wind charge to cast it

at level 15 you may cast counterspell at level 4